Commonly, indicator displays for automotive vehicles comprise a number of compartments each of which is associated with one particular function, for example position, braking, fog lamp operation, direction indication, etc. Each compartment contains an electric light bulb or indicator lamp, with an electrical circuit associated with the display controlling the selection of the power supply to the indicator lamps.
When regulations permit, one common compartment may be used for indicating two functions, for example position and braking, or position and fog light operation. A single lamp of the double filament kind is used to ensure, for each function, the required luminous intensity for the corresponding function.
These conventional indicator displays have a number of disadvantages. The most significant of these is the substantial depth (from front to back) of the display itself, which is necessitated by the deep recesses which have to be provided in the bodywork. This depth leads to a considerable loss of useful space, in particular in the instrument panel. In addition, these displays, having one single lamp for each function, call for optical means for distributing the emitted light, the source of which is a point source. It is difficult to avoid, in the lighting arrangement, the phenomenon whereby one point appears brighter than others and which may indeed dazzle.
To overcome these disadvantages it has been proposed to use for each function a plurality of miniature lamps. These miniature lamps, which only have a single filament, do not allow several functions to be displayed.
In French published patent application No. 1 363 551, it has been proposed, for a conventional display having one lamp per function, to shunt as required a resistor in the supply circuit for a lamp, in order to ensure, for that particular function, a luminous intensity which can be made different according to local regulations or conditions of use, for example whether it is day or night. This known indicator display has the same disadvantages as the conventional displays, and also requires complicated connections.